Diaphorases (EC.1.6.99.-) play an important role in electron transport systems in vivo.
In various technical fields, the use of diaphorases in vitro has been studied and some of them have been put to practical use. Examples of such technical fields include the production of useful material, the production, measurement or analysis of energy-related material, environmental protection, medical, and other fields. For example, in the field of clinical diagnosis, utilizing the property of diaphorases that it uses reduced nicotinamide adenine dinucleotide (NADH) or reduced nicotinamide adenine dinucleotide phosphate phosphate (NADPH) as a substrate, diaphorases are used to form various in vitro diagnostic reagents. A diaphorase is also used as an enzyme cell, which is one type of fuel cell (Patent Document 9, Patent Document 10, Patent Document 11, Non-patent Document 1).
Commercially available diaphorases include those isolated and purified from microorganisms that belong to the genus Clostridium (Non-patent Document 2) or Bacillus (Patent Document 1, Patent Document 2). Bacillus stearothermophilus that is capable of producing the diaphorase described in Patent Document 1 and Patent Document 2 was reclassified as Geobacillus stearothermophilus in 2001 (Non-patent Document 3). Diaphorase derived from Geobacillus stearothermophilus and modifications thereof are also known, and their gene sequences, amino acid sequences, and physicochemical characteristics are being studied (Patent Document 2, Patent Document 3, Patent Document 8, and Non-patent Document 1).